This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. This study will test the hypothesis that a recently discovered hormone synthesized by the small intestine, glucose-dependent insulinotropic polypeptide(GIP), has a role in brain signaling related to sensing body glucose availability. This will be done by estimating insulin sensitivity to an oral glucose challenge in baboons before and after chronically increasing brain GIP levels.